Thermal battery cells containing novel cathode materials in an oxyanionic electrolyte

Abstract

The addition of cathode materials comprising In +++ , Pb ++ or Cd ++ ion, e.g. in the form of salts such as In(NO 3 ) 3 , Pb(NO 3 ) 2 , Cd(NO 3 ) 2 or the corresponding perchlorates, to oxyanionic electrolyte cells increases cell potential. Such cathodic materials are added to lower melting fused salt oxyanionic electrolytes such as nitrate or perchlorate electrolytes, e.g. LiNO 3 , KNO 3 or LiCl0 4 , in a concentration sufficient to increase cell potential, using Li or Ca anodes. A suitable metal current collector such as a Ni screen can be used as a cathode. The above cathodic materials can be used in conjunction with other cathodic materials such as AgNO 3 , which undergoes reduction to the free metal.

What is claimed is: 
     
       1. A thermal electrochemical cell comprising an oxyanionic electrolyte which is a non-conductive solid at ambient temperature and is capable of becoming an ionically conductive liquid upon being heated above its melting point,   a cathode material in said electrolyte, said cathode material comprising a metal ion selected from the group consisting In +++ , Pb ++  and Cd ++  ions, and mixtures thereof, and   an anode in contact with said electrolyte, selected from the group consisting of Li and Ca anodes.   
     
     
       2. The thermal cell of claim 1, said oxyanionic electrolyte being selected from the group consisting of nitrite, nitrate, chlorate, sulfate and sulfite salts. 
     
     
       3. The thermal cell of claim 1, said oxyanionic electrolyte selected from the group consisting of nitrate, nitrite and perchlorate salts, and mixtures thereof. 
     
     
       4. The thermal cell of claim 3, said oxyanionic electrolyte selected from the group consisting of LiNO 3  /KNO 3 , LiClO 4  /KClO 4 , NaNO 3  /KNO 3  and NaNO 2  /KNO 3  /NaNO 3 . 
     
     
       5. The thermal cell of claim 1, wherein said cathode material is derived from a salt containing said metal ion, said salt being soluble in said electrolyte. 
     
     
       6. The thermal cell of claim 5, wherein said cathode material is selected from the group consisting of In(NO 3 ) 3 , Pb(NO 3 ) 2 , Cd(NO 3 ) 2  and Pb(ClO 4 ) 2 . 
     
     
       7. The thermal cell of claim 5, wherein the concentration of said cathode material in said electrolyte ranges from about 2×10 -4  to about 2×10 -1  molal. 
     
     
       8. The thermal cell of claim 5, and including a cathode current collector in contact with said electrolyte and spaced from said anode. 
     
     
       9. The thermal cell of claim 5, said metal salt cathode material comprising a solid layer in said electrolyte spaced from said anode. 
     
     
       10. The thermal cell of claim 5, said cathode material also including a silver salt in a proportion of about 0.01 to about 1 mole per mole of said salt containing said metal ion. 
     
     
       11. The thermal cell of claim 6, wherein said electrolyte is a nitrate electrolyte. 
     
     
       12. The thermal cell of claim 11, wherein said electrolyte is LiNO 3  /KNO 3 , and wherein the concentration of said cathode material is said electrolyte ranges from about 2×10 -4  to about 2×10 -1  molal. 
     
     
       13. The thermal cell of claim 6, wherein said electrolyte is a perchlorate electrolyte. 
     
     
       14. The thermal cell of claim 13, wherein said electrolyte is LiClO 4  /KClO 4 , and wherein the concentration of said cathode material in said electrolyte ranges from about 2×10 -4  to about 2×10 -1  molal. 
     
     
       15. In a thermal electrochemical cell comprising an anode, a cathode and an electrolyte disposed between said anode and said cathode, an oxyanionic electrolyte which is a non-conductive solid at ambient temperature and is capable of becoming an ionically conductive liquid upon being heated above its melting point,   a cathode material diffused in said electrolyte, said cathode material comprising a metal ion selected from the group consisting of In +++ , Pb ++  and Cd ++  ions, and mixtures thereof, and   an anode in contact with said electrolyte, and selected from the group consisting of Li and Ca anodes.   
     
     
       16. The thermal cell of claim 15, said oxyanionic electrolyte selected from the group consisting of LiNO 3  /KNO 3 , LiClO 4  /KClO 4 , NaNO 3  /KNO 3  and NaNO 2  /KNO 3  /NaNO 3 . 
     
     
       17. The thermal cell of claim 16, wherein said cathode material is selected from the group consisting of In(NO 3 ) 3 , Pb(NO 3 ) 2 , Cd(NO 3 ) 2  and Pb(ClO 4 ) 2 . 
     
     
       18. The thermal cell of claim 17, wherein the concentration of said cathode material in said electrolyte ranges from about 2×10 -4  to about 2×10 -1  molal. 
     
     
       19. The thermal cell of claim 18, and including a cathode current collector in contact with said electrolyte and spaced from said anode.